You ask reasonable questions and there does indeed come into play considerations of tastes and personal preferences. In addition, relative resale value for those that have changing interests or may aspire to "upgrade" later on.
These are my opinions based upon aesthetics and resale value, not functionality.
1.) Heyms in standard 88B configuration are ugly. They did make some that were not ugly through rounding the action, prudent engraving, or adding sideplates, or being true sidelocks. But be that as it may, it effected their marketshare in default configuration enough that they made the 89B which is a stunningly "British" rifle. Nonetheless, Heyms hold their values better than any other double rifle in the world, bar none. A used $12,000-$17,000 Heym is a LOT of gun for the money. When/If resold at a later date, the buyer can pretty much count on a return of most or all their money if they bought one used. If they bought a new one, they may have lost only 30% which is unprecedented. Interestingly enough, the base PH model 88B that most agree is fairly ugly still holds its value. Proof that good looks can be trumped by professional reputation.
2.) Krieghoffs have their fanbase. It's a pretty specific circle that buys them. Every owner I know personally is active into K80 collecting and live pigeon shooting. Retired guys that like K-guns so they bought more K-guns. They have a very ingenious safety system that is loved by some and loathed by many. Of all the double rifles, they hold their values the worst. If we are talking about pretty/ugly debates, the majority find Krieghoffs to be the most amateurish in their engraving and contoured lines. A reader may love them, but
the market votes them as both ugly and as peculiar in their safety when it comes to resale value.
3.) For value and longterm appreciation, the market deems the English guns to be the most beautiful and to hold their tertiary resale value to be the highest. The problems are A.) You need to know what you're buying as a heavily restored gun poorly executed has little worth, B.) While any skilled gunsmith can service an Anson & Deeley boxlock, you've likely got no original manufacturer to run back to if something catastrophic happens to a vintage gun, C.) Most are wholly incompatible with modern mono-metal solids which diminishes utility.
@Rare Breed recently made an excellent purchase of an ideal restored example and I'd say the tradeoff of not using monometals was a pretty good surrender of requirements in exchange to own and hunt with a gun of that overall quality and aesthetic standard. The inefficient marketplace resulted in him buying something low in one region (Safari gun sold in France) to be acquired in a place of low supply and stronger demand. ('Merica)
Like boats, people can fall in love with any which one they want and nobody can undermine your personal opinion of what is beautiful. But if resale is ever a consideration, like boats, most guns lose a fortune because personal tastes are trumped by blue-book values of the broader market.
